1. Field of the Invention
The present invention relates to a semiconductor device for reducing a resistance value in a pad electrode formation part, and a manufacturing method thereof.
2. Description of the Related Art
As an example of a conventional method for manufacturing a semiconductor device, the following manufacturing method as shown in FIGS. 18A to 18F has been known. As shown in FIG. 18A, an interlayer insulating film 92 made of silicon dioxide or the like is formed on a surface of a silicon substrate 91. Next, as shown in FIG. 18B, an aluminum (Al) electrode pad 93 having a thickness of about 1.0 (μm) is formed on the interlayer insulating film 92. Thereafter, as shown in FIG. 18C, a silicon nitride film 94 is formed on the Al electrode pad 93 and the interlayer insulating film 92 by use of a CVD (chemical vapor deposition) method. Subsequently, as shown in FIG. 18D, an opening 95 is formed in the silicon nitride film 94 on the Al electrode pad 93. Next, as shown in FIG. 18E, a barrier metal film 96 is formed so as to cover the Al electrode pad 93 exposed from the opening 95. Thereafter, as shown in FIG. 18F, a gold bump 97 is formed on the barrier metal film 96 by use of an electrolytic plating method. This technology is described for instance in Japanese Patent Application Publication No. Hei 11-145171 (Pages 2 and 3, FIG. 1).
As described above, in the conventional method for manufacturing a semiconductor device, after the Al electrode pad 93 is formed on the interlayer insulating film 92, the silicon nitride film 94 as a passivation film is formed on the Al electrode pad 93. After the opening 95 is formed in the silicon nitride film 94 on the Al electrode pad 93, the barrier metal film 96 is formed on the exposed Al electrode pad 93 by use of a sputtering method, for example. According to this manufacturing method, in the step of forming the opening 95 in the silicon nitride film 94 and forming the barrier metal film 96 therein, the Al electrode pad 93 exposed from the opening 95 is oxidized to form an oxide film on the Al electrode pad 93. Thus, a current path on the Al electrode pad 93 is from the Al electrode pad 93 to the gold bump 97 through the oxide film on the Al electrode pad 93 and the barrier metal film 96. As a result, there is a problem that the oxide film formed on the current path makes it difficult to reduce a resistance value on the Al electrode pad 93.